Why do some people pronounce immediately immediantely?

You're right, "immediately" is sometimes pronounced as "immediantely" - with an extra "n" sound. This is an example of a common pronunciation error, often stemming from:

* Mishearing: People might mishear the word being pronounced with the extra "n" sound, and simply repeat what they heard.

* Overgeneralization: The "n" sound in words like "instant" and "instantaneous" might lead people to assume it should also be present in "immediately".

* Influence of other languages: Some languages have similar sounding words where the "n" sound is present, leading to a transfer of this pronunciation into English.

However, the correct pronunciation of "immediately" is "im-me-di-at-ly" - without the extra "n" sound.

It's important to note that pronunciation variations can occur across different dialects and regions. While "immediantely" might be considered incorrect in standard English, it could be a perfectly acceptable pronunciation in certain regional dialects.